Commit | Line | Data |
---|---|---|
5274f052 JA |
1 | /* |
2 | * "splice": joining two ropes together by interweaving their strands. | |
3 | * | |
4 | * This is the "extended pipe" functionality, where a pipe is used as | |
5 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel | |
6 | * buffer that you can use to transfer data from one end to the other. | |
7 | * | |
8 | * The traditional unix read/write is extended with a "splice()" operation | |
9 | * that transfers data buffers to or from a pipe buffer. | |
10 | * | |
11 | * Named by Larry McVoy, original implementation from Linus, extended by | |
c2058e06 JA |
12 | * Jens to support splicing to files, network, direct splicing, etc and |
13 | * fixing lots of bugs. | |
5274f052 | 14 | * |
0fe23479 | 15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
c2058e06 JA |
16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> | |
5274f052 JA |
18 | * |
19 | */ | |
20 | #include <linux/fs.h> | |
21 | #include <linux/file.h> | |
22 | #include <linux/pagemap.h> | |
d6b29d7c | 23 | #include <linux/splice.h> |
08e552c6 | 24 | #include <linux/memcontrol.h> |
5274f052 | 25 | #include <linux/mm_inline.h> |
5abc97aa | 26 | #include <linux/swap.h> |
4f6f0bd2 | 27 | #include <linux/writeback.h> |
630d9c47 | 28 | #include <linux/export.h> |
4f6f0bd2 | 29 | #include <linux/syscalls.h> |
912d35f8 | 30 | #include <linux/uio.h> |
29ce2058 | 31 | #include <linux/security.h> |
5a0e3ad6 | 32 | #include <linux/gfp.h> |
35f9c09f | 33 | #include <linux/socket.h> |
76b021d0 | 34 | #include <linux/compat.h> |
06ae43f3 | 35 | #include "internal.h" |
5274f052 | 36 | |
83f9135b JA |
37 | /* |
38 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
39 | * a vm helper function, it's already simplified quite a bit by the | |
40 | * addition of remove_mapping(). If success is returned, the caller may | |
41 | * attempt to reuse this page for another destination. | |
42 | */ | |
76ad4d11 | 43 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
5abc97aa JA |
44 | struct pipe_buffer *buf) |
45 | { | |
46 | struct page *page = buf->page; | |
9e94cd4f | 47 | struct address_space *mapping; |
5abc97aa | 48 | |
9e0267c2 JA |
49 | lock_page(page); |
50 | ||
9e94cd4f JA |
51 | mapping = page_mapping(page); |
52 | if (mapping) { | |
53 | WARN_ON(!PageUptodate(page)); | |
5abc97aa | 54 | |
9e94cd4f JA |
55 | /* |
56 | * At least for ext2 with nobh option, we need to wait on | |
57 | * writeback completing on this page, since we'll remove it | |
58 | * from the pagecache. Otherwise truncate wont wait on the | |
59 | * page, allowing the disk blocks to be reused by someone else | |
60 | * before we actually wrote our data to them. fs corruption | |
61 | * ensues. | |
62 | */ | |
63 | wait_on_page_writeback(page); | |
ad8d6f0a | 64 | |
266cf658 DH |
65 | if (page_has_private(page) && |
66 | !try_to_release_page(page, GFP_KERNEL)) | |
ca39d651 | 67 | goto out_unlock; |
4f6f0bd2 | 68 | |
9e94cd4f JA |
69 | /* |
70 | * If we succeeded in removing the mapping, set LRU flag | |
71 | * and return good. | |
72 | */ | |
73 | if (remove_mapping(mapping, page)) { | |
74 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
75 | return 0; | |
76 | } | |
9e0267c2 | 77 | } |
5abc97aa | 78 | |
9e94cd4f JA |
79 | /* |
80 | * Raced with truncate or failed to remove page from current | |
81 | * address space, unlock and return failure. | |
82 | */ | |
ca39d651 | 83 | out_unlock: |
9e94cd4f JA |
84 | unlock_page(page); |
85 | return 1; | |
5abc97aa JA |
86 | } |
87 | ||
76ad4d11 | 88 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
5274f052 JA |
89 | struct pipe_buffer *buf) |
90 | { | |
09cbfeaf | 91 | put_page(buf->page); |
1432873a | 92 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
5274f052 JA |
93 | } |
94 | ||
0845718d JA |
95 | /* |
96 | * Check whether the contents of buf is OK to access. Since the content | |
97 | * is a page cache page, IO may be in flight. | |
98 | */ | |
cac36bb0 JA |
99 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
100 | struct pipe_buffer *buf) | |
5274f052 JA |
101 | { |
102 | struct page *page = buf->page; | |
49d0b21b | 103 | int err; |
5274f052 JA |
104 | |
105 | if (!PageUptodate(page)) { | |
49d0b21b JA |
106 | lock_page(page); |
107 | ||
108 | /* | |
109 | * Page got truncated/unhashed. This will cause a 0-byte | |
73d62d83 | 110 | * splice, if this is the first page. |
49d0b21b JA |
111 | */ |
112 | if (!page->mapping) { | |
113 | err = -ENODATA; | |
114 | goto error; | |
115 | } | |
5274f052 | 116 | |
49d0b21b | 117 | /* |
73d62d83 | 118 | * Uh oh, read-error from disk. |
49d0b21b JA |
119 | */ |
120 | if (!PageUptodate(page)) { | |
121 | err = -EIO; | |
122 | goto error; | |
123 | } | |
124 | ||
125 | /* | |
f84d7519 | 126 | * Page is ok afterall, we are done. |
49d0b21b | 127 | */ |
5274f052 | 128 | unlock_page(page); |
5274f052 JA |
129 | } |
130 | ||
f84d7519 | 131 | return 0; |
49d0b21b JA |
132 | error: |
133 | unlock_page(page); | |
f84d7519 | 134 | return err; |
70524490 JA |
135 | } |
136 | ||
708e3508 | 137 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
5274f052 | 138 | .can_merge = 0, |
cac36bb0 | 139 | .confirm = page_cache_pipe_buf_confirm, |
5274f052 | 140 | .release = page_cache_pipe_buf_release, |
5abc97aa | 141 | .steal = page_cache_pipe_buf_steal, |
f84d7519 | 142 | .get = generic_pipe_buf_get, |
5274f052 JA |
143 | }; |
144 | ||
912d35f8 JA |
145 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
146 | struct pipe_buffer *buf) | |
147 | { | |
7afa6fd0 JA |
148 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
149 | return 1; | |
150 | ||
1432873a | 151 | buf->flags |= PIPE_BUF_FLAG_LRU; |
330ab716 | 152 | return generic_pipe_buf_steal(pipe, buf); |
912d35f8 JA |
153 | } |
154 | ||
d4c3cca9 | 155 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
912d35f8 | 156 | .can_merge = 0, |
cac36bb0 | 157 | .confirm = generic_pipe_buf_confirm, |
912d35f8 JA |
158 | .release = page_cache_pipe_buf_release, |
159 | .steal = user_page_pipe_buf_steal, | |
f84d7519 | 160 | .get = generic_pipe_buf_get, |
912d35f8 JA |
161 | }; |
162 | ||
825cdcb1 NK |
163 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
164 | { | |
165 | smp_mb(); | |
166 | if (waitqueue_active(&pipe->wait)) | |
167 | wake_up_interruptible(&pipe->wait); | |
168 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); | |
169 | } | |
170 | ||
932cc6d4 JA |
171 | /** |
172 | * splice_to_pipe - fill passed data into a pipe | |
173 | * @pipe: pipe to fill | |
174 | * @spd: data to fill | |
175 | * | |
176 | * Description: | |
79685b8d | 177 | * @spd contains a map of pages and len/offset tuples, along with |
932cc6d4 JA |
178 | * the struct pipe_buf_operations associated with these pages. This |
179 | * function will link that data to the pipe. | |
180 | * | |
83f9135b | 181 | */ |
d6b29d7c JA |
182 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
183 | struct splice_pipe_desc *spd) | |
5274f052 | 184 | { |
00de00bd | 185 | unsigned int spd_pages = spd->nr_pages; |
8924feff | 186 | int ret = 0, page_nr = 0; |
5274f052 | 187 | |
d6785d91 RV |
188 | if (!spd_pages) |
189 | return 0; | |
190 | ||
8924feff AV |
191 | if (unlikely(!pipe->readers)) { |
192 | send_sig(SIGPIPE, current, 0); | |
193 | ret = -EPIPE; | |
194 | goto out; | |
195 | } | |
5274f052 | 196 | |
8924feff AV |
197 | while (pipe->nrbufs < pipe->buffers) { |
198 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
199 | struct pipe_buffer *buf = pipe->bufs + newbuf; | |
5274f052 | 200 | |
8924feff AV |
201 | buf->page = spd->pages[page_nr]; |
202 | buf->offset = spd->partial[page_nr].offset; | |
203 | buf->len = spd->partial[page_nr].len; | |
204 | buf->private = spd->partial[page_nr].private; | |
205 | buf->ops = spd->ops; | |
5274f052 | 206 | |
8924feff AV |
207 | pipe->nrbufs++; |
208 | page_nr++; | |
209 | ret += buf->len; | |
29e35094 | 210 | |
8924feff | 211 | if (!--spd->nr_pages) |
5274f052 | 212 | break; |
5274f052 JA |
213 | } |
214 | ||
8924feff AV |
215 | if (!ret) |
216 | ret = -EAGAIN; | |
5274f052 | 217 | |
8924feff | 218 | out: |
00de00bd | 219 | while (page_nr < spd_pages) |
bbdfc2f7 | 220 | spd->spd_release(spd, page_nr++); |
5274f052 JA |
221 | |
222 | return ret; | |
223 | } | |
2b514574 | 224 | EXPORT_SYMBOL_GPL(splice_to_pipe); |
5274f052 | 225 | |
79fddc4e AV |
226 | ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
227 | { | |
228 | int ret; | |
229 | ||
230 | if (unlikely(!pipe->readers)) { | |
231 | send_sig(SIGPIPE, current, 0); | |
232 | ret = -EPIPE; | |
233 | } else if (pipe->nrbufs == pipe->buffers) { | |
234 | ret = -EAGAIN; | |
235 | } else { | |
236 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
237 | pipe->bufs[newbuf] = *buf; | |
238 | pipe->nrbufs++; | |
239 | return buf->len; | |
240 | } | |
241 | buf->ops->release(pipe, buf); | |
242 | buf->ops = NULL; | |
243 | return ret; | |
244 | } | |
245 | EXPORT_SYMBOL(add_to_pipe); | |
246 | ||
708e3508 | 247 | void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
bbdfc2f7 | 248 | { |
09cbfeaf | 249 | put_page(spd->pages[i]); |
bbdfc2f7 JA |
250 | } |
251 | ||
35f3d14d JA |
252 | /* |
253 | * Check if we need to grow the arrays holding pages and partial page | |
254 | * descriptions. | |
255 | */ | |
047fe360 | 256 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
35f3d14d | 257 | { |
047fe360 ED |
258 | unsigned int buffers = ACCESS_ONCE(pipe->buffers); |
259 | ||
260 | spd->nr_pages_max = buffers; | |
261 | if (buffers <= PIPE_DEF_BUFFERS) | |
35f3d14d JA |
262 | return 0; |
263 | ||
047fe360 ED |
264 | spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL); |
265 | spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL); | |
35f3d14d JA |
266 | |
267 | if (spd->pages && spd->partial) | |
268 | return 0; | |
269 | ||
270 | kfree(spd->pages); | |
271 | kfree(spd->partial); | |
272 | return -ENOMEM; | |
273 | } | |
274 | ||
047fe360 | 275 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
35f3d14d | 276 | { |
047fe360 | 277 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
35f3d14d JA |
278 | return; |
279 | ||
280 | kfree(spd->pages); | |
281 | kfree(spd->partial); | |
282 | } | |
283 | ||
83f9135b JA |
284 | /** |
285 | * generic_file_splice_read - splice data from file to a pipe | |
286 | * @in: file to splice from | |
932cc6d4 | 287 | * @ppos: position in @in |
83f9135b JA |
288 | * @pipe: pipe to splice to |
289 | * @len: number of bytes to splice | |
290 | * @flags: splice modifier flags | |
291 | * | |
932cc6d4 JA |
292 | * Description: |
293 | * Will read pages from given file and fill them into a pipe. Can be | |
82c156f8 | 294 | * used as long as it has more or less sane ->read_iter(). |
932cc6d4 | 295 | * |
83f9135b | 296 | */ |
cbb7e577 JA |
297 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
298 | struct pipe_inode_info *pipe, size_t len, | |
299 | unsigned int flags) | |
5274f052 | 300 | { |
82c156f8 AV |
301 | struct iov_iter to; |
302 | struct kiocb kiocb; | |
303 | loff_t isize; | |
304 | int idx, ret; | |
be64f884 | 305 | |
d366d398 JA |
306 | isize = i_size_read(in->f_mapping->host); |
307 | if (unlikely(*ppos >= isize)) | |
308 | return 0; | |
309 | ||
82c156f8 AV |
310 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len); |
311 | idx = to.idx; | |
312 | init_sync_kiocb(&kiocb, in); | |
313 | kiocb.ki_pos = *ppos; | |
314 | ret = in->f_op->read_iter(&kiocb, &to); | |
723590ed | 315 | if (ret > 0) { |
82c156f8 | 316 | *ppos = kiocb.ki_pos; |
723590ed | 317 | file_accessed(in); |
82c156f8 AV |
318 | } else if (ret < 0) { |
319 | if (WARN_ON(to.idx != idx || to.iov_offset)) { | |
320 | /* | |
321 | * a bogus ->read_iter() has copied something and still | |
322 | * returned an error instead of a short read. | |
323 | */ | |
324 | to.idx = idx; | |
325 | to.iov_offset = 0; | |
326 | iov_iter_advance(&to, 0); /* to free what was emitted */ | |
327 | } | |
328 | /* | |
329 | * callers of ->splice_read() expect -EAGAIN on | |
330 | * "can't put anything in there", rather than -EFAULT. | |
331 | */ | |
332 | if (ret == -EFAULT) | |
333 | ret = -EAGAIN; | |
723590ed | 334 | } |
5274f052 JA |
335 | |
336 | return ret; | |
337 | } | |
059a8f37 JA |
338 | EXPORT_SYMBOL(generic_file_splice_read); |
339 | ||
241699cd | 340 | const struct pipe_buf_operations default_pipe_buf_ops = { |
6818173b | 341 | .can_merge = 0, |
6818173b MS |
342 | .confirm = generic_pipe_buf_confirm, |
343 | .release = generic_pipe_buf_release, | |
344 | .steal = generic_pipe_buf_steal, | |
345 | .get = generic_pipe_buf_get, | |
346 | }; | |
347 | ||
28a625cb MS |
348 | static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe, |
349 | struct pipe_buffer *buf) | |
350 | { | |
351 | return 1; | |
352 | } | |
353 | ||
354 | /* Pipe buffer operations for a socket and similar. */ | |
355 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { | |
356 | .can_merge = 0, | |
28a625cb MS |
357 | .confirm = generic_pipe_buf_confirm, |
358 | .release = generic_pipe_buf_release, | |
359 | .steal = generic_pipe_buf_nosteal, | |
360 | .get = generic_pipe_buf_get, | |
361 | }; | |
362 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); | |
363 | ||
523ac9af | 364 | static ssize_t kernel_readv(struct file *file, const struct kvec *vec, |
6818173b MS |
365 | unsigned long vlen, loff_t offset) |
366 | { | |
367 | mm_segment_t old_fs; | |
368 | loff_t pos = offset; | |
369 | ssize_t res; | |
370 | ||
371 | old_fs = get_fs(); | |
372 | set_fs(get_ds()); | |
373 | /* The cast to a user pointer is valid due to the set_fs() */ | |
793b80ef | 374 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0); |
6818173b MS |
375 | set_fs(old_fs); |
376 | ||
377 | return res; | |
378 | } | |
379 | ||
7bb307e8 | 380 | ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
b2858d7d | 381 | loff_t pos) |
0b0a47f5 MS |
382 | { |
383 | mm_segment_t old_fs; | |
384 | ssize_t res; | |
385 | ||
386 | old_fs = get_fs(); | |
387 | set_fs(get_ds()); | |
388 | /* The cast to a user pointer is valid due to the set_fs() */ | |
7bb307e8 | 389 | res = vfs_write(file, (__force const char __user *)buf, count, &pos); |
0b0a47f5 MS |
390 | set_fs(old_fs); |
391 | ||
392 | return res; | |
393 | } | |
7bb307e8 | 394 | EXPORT_SYMBOL(kernel_write); |
0b0a47f5 | 395 | |
82c156f8 | 396 | static ssize_t default_file_splice_read(struct file *in, loff_t *ppos, |
6818173b MS |
397 | struct pipe_inode_info *pipe, size_t len, |
398 | unsigned int flags) | |
399 | { | |
523ac9af AV |
400 | struct kvec *vec, __vec[PIPE_DEF_BUFFERS]; |
401 | struct iov_iter to; | |
402 | struct page **pages; | |
6818173b | 403 | unsigned int nr_pages; |
523ac9af | 404 | size_t offset, dummy, copied = 0; |
6818173b | 405 | ssize_t res; |
6818173b | 406 | int i; |
35f3d14d | 407 | |
523ac9af AV |
408 | if (pipe->nrbufs == pipe->buffers) |
409 | return -EAGAIN; | |
35f3d14d | 410 | |
523ac9af AV |
411 | /* |
412 | * Try to keep page boundaries matching to source pagecache ones - | |
413 | * it probably won't be much help, but... | |
414 | */ | |
09cbfeaf | 415 | offset = *ppos & ~PAGE_MASK; |
6818173b | 416 | |
523ac9af | 417 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset); |
6818173b | 418 | |
523ac9af AV |
419 | res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &dummy); |
420 | if (res <= 0) | |
421 | return -ENOMEM; | |
6818173b | 422 | |
523ac9af | 423 | nr_pages = res / PAGE_SIZE; |
6818173b | 424 | |
523ac9af AV |
425 | vec = __vec; |
426 | if (nr_pages > PIPE_DEF_BUFFERS) { | |
427 | vec = kmalloc(nr_pages * sizeof(struct kvec), GFP_KERNEL); | |
428 | if (unlikely(!vec)) { | |
429 | res = -ENOMEM; | |
430 | goto out; | |
431 | } | |
77f6bf57 | 432 | } |
6818173b | 433 | |
523ac9af AV |
434 | pipe->bufs[to.idx].offset = offset; |
435 | pipe->bufs[to.idx].len -= offset; | |
436 | ||
437 | for (i = 0; i < nr_pages; i++) { | |
438 | size_t this_len = min_t(size_t, len, PAGE_SIZE - offset); | |
439 | vec[i].iov_base = page_address(pages[i]) + offset; | |
440 | vec[i].iov_len = this_len; | |
441 | len -= this_len; | |
442 | offset = 0; | |
6818173b | 443 | } |
6818173b | 444 | |
523ac9af AV |
445 | res = kernel_readv(in, vec, nr_pages, *ppos); |
446 | if (res > 0) { | |
447 | copied = res; | |
6818173b | 448 | *ppos += res; |
523ac9af | 449 | } |
6818173b | 450 | |
35f3d14d JA |
451 | if (vec != __vec) |
452 | kfree(vec); | |
523ac9af AV |
453 | out: |
454 | for (i = 0; i < nr_pages; i++) | |
455 | put_page(pages[i]); | |
456 | kvfree(pages); | |
457 | iov_iter_advance(&to, copied); /* truncates and discards */ | |
6818173b | 458 | return res; |
6818173b | 459 | } |
6818173b | 460 | |
5274f052 | 461 | /* |
4f6f0bd2 | 462 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 463 | * using sendpage(). Return the number of bytes sent. |
5274f052 | 464 | */ |
76ad4d11 | 465 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
5274f052 JA |
466 | struct pipe_buffer *buf, struct splice_desc *sd) |
467 | { | |
6a14b90b | 468 | struct file *file = sd->u.file; |
5274f052 | 469 | loff_t pos = sd->pos; |
a8adbe37 | 470 | int more; |
5274f052 | 471 | |
72c2d531 | 472 | if (!likely(file->f_op->sendpage)) |
a8adbe37 MM |
473 | return -EINVAL; |
474 | ||
35f9c09f | 475 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
ae62ca7b ED |
476 | |
477 | if (sd->len < sd->total_len && pipe->nrbufs > 1) | |
35f9c09f | 478 | more |= MSG_SENDPAGE_NOTLAST; |
ae62ca7b | 479 | |
a8adbe37 MM |
480 | return file->f_op->sendpage(file, buf->page, buf->offset, |
481 | sd->len, &pos, more); | |
5274f052 JA |
482 | } |
483 | ||
b3c2d2dd MS |
484 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
485 | { | |
486 | smp_mb(); | |
487 | if (waitqueue_active(&pipe->wait)) | |
488 | wake_up_interruptible(&pipe->wait); | |
489 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
490 | } | |
491 | ||
932cc6d4 | 492 | /** |
b3c2d2dd | 493 | * splice_from_pipe_feed - feed available data from a pipe to a file |
932cc6d4 JA |
494 | * @pipe: pipe to splice from |
495 | * @sd: information to @actor | |
496 | * @actor: handler that splices the data | |
497 | * | |
498 | * Description: | |
b3c2d2dd MS |
499 | * This function loops over the pipe and calls @actor to do the |
500 | * actual moving of a single struct pipe_buffer to the desired | |
501 | * destination. It returns when there's no more buffers left in | |
502 | * the pipe or if the requested number of bytes (@sd->total_len) | |
503 | * have been copied. It returns a positive number (one) if the | |
504 | * pipe needs to be filled with more data, zero if the required | |
505 | * number of bytes have been copied and -errno on error. | |
932cc6d4 | 506 | * |
b3c2d2dd MS |
507 | * This, together with splice_from_pipe_{begin,end,next}, may be |
508 | * used to implement the functionality of __splice_from_pipe() when | |
509 | * locking is required around copying the pipe buffers to the | |
510 | * destination. | |
83f9135b | 511 | */ |
96f9bc8f | 512 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
b3c2d2dd | 513 | splice_actor *actor) |
5274f052 | 514 | { |
b3c2d2dd | 515 | int ret; |
5274f052 | 516 | |
b3c2d2dd MS |
517 | while (pipe->nrbufs) { |
518 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
519 | const struct pipe_buf_operations *ops = buf->ops; | |
5274f052 | 520 | |
b3c2d2dd MS |
521 | sd->len = buf->len; |
522 | if (sd->len > sd->total_len) | |
523 | sd->len = sd->total_len; | |
5274f052 | 524 | |
a8adbe37 MM |
525 | ret = buf->ops->confirm(pipe, buf); |
526 | if (unlikely(ret)) { | |
b3c2d2dd MS |
527 | if (ret == -ENODATA) |
528 | ret = 0; | |
529 | return ret; | |
530 | } | |
a8adbe37 MM |
531 | |
532 | ret = actor(pipe, buf, sd); | |
533 | if (ret <= 0) | |
534 | return ret; | |
535 | ||
b3c2d2dd MS |
536 | buf->offset += ret; |
537 | buf->len -= ret; | |
538 | ||
539 | sd->num_spliced += ret; | |
540 | sd->len -= ret; | |
541 | sd->pos += ret; | |
542 | sd->total_len -= ret; | |
543 | ||
544 | if (!buf->len) { | |
545 | buf->ops = NULL; | |
546 | ops->release(pipe, buf); | |
35f3d14d | 547 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
b3c2d2dd | 548 | pipe->nrbufs--; |
6447a3cf | 549 | if (pipe->files) |
b3c2d2dd MS |
550 | sd->need_wakeup = true; |
551 | } | |
5274f052 | 552 | |
b3c2d2dd MS |
553 | if (!sd->total_len) |
554 | return 0; | |
555 | } | |
5274f052 | 556 | |
b3c2d2dd MS |
557 | return 1; |
558 | } | |
5274f052 | 559 | |
b3c2d2dd MS |
560 | /** |
561 | * splice_from_pipe_next - wait for some data to splice from | |
562 | * @pipe: pipe to splice from | |
563 | * @sd: information about the splice operation | |
564 | * | |
565 | * Description: | |
566 | * This function will wait for some data and return a positive | |
567 | * value (one) if pipe buffers are available. It will return zero | |
568 | * or -errno if no more data needs to be spliced. | |
569 | */ | |
96f9bc8f | 570 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd | 571 | { |
c725bfce JK |
572 | /* |
573 | * Check for signal early to make process killable when there are | |
574 | * always buffers available | |
575 | */ | |
576 | if (signal_pending(current)) | |
577 | return -ERESTARTSYS; | |
578 | ||
b3c2d2dd MS |
579 | while (!pipe->nrbufs) { |
580 | if (!pipe->writers) | |
581 | return 0; | |
016b661e | 582 | |
b3c2d2dd MS |
583 | if (!pipe->waiting_writers && sd->num_spliced) |
584 | return 0; | |
73d62d83 | 585 | |
b3c2d2dd MS |
586 | if (sd->flags & SPLICE_F_NONBLOCK) |
587 | return -EAGAIN; | |
5274f052 | 588 | |
b3c2d2dd MS |
589 | if (signal_pending(current)) |
590 | return -ERESTARTSYS; | |
5274f052 | 591 | |
b3c2d2dd MS |
592 | if (sd->need_wakeup) { |
593 | wakeup_pipe_writers(pipe); | |
594 | sd->need_wakeup = false; | |
5274f052 JA |
595 | } |
596 | ||
b3c2d2dd MS |
597 | pipe_wait(pipe); |
598 | } | |
29e35094 | 599 | |
b3c2d2dd MS |
600 | return 1; |
601 | } | |
5274f052 | 602 | |
b3c2d2dd MS |
603 | /** |
604 | * splice_from_pipe_begin - start splicing from pipe | |
b80901bb | 605 | * @sd: information about the splice operation |
b3c2d2dd MS |
606 | * |
607 | * Description: | |
608 | * This function should be called before a loop containing | |
609 | * splice_from_pipe_next() and splice_from_pipe_feed() to | |
610 | * initialize the necessary fields of @sd. | |
611 | */ | |
96f9bc8f | 612 | static void splice_from_pipe_begin(struct splice_desc *sd) |
b3c2d2dd MS |
613 | { |
614 | sd->num_spliced = 0; | |
615 | sd->need_wakeup = false; | |
616 | } | |
5274f052 | 617 | |
b3c2d2dd MS |
618 | /** |
619 | * splice_from_pipe_end - finish splicing from pipe | |
620 | * @pipe: pipe to splice from | |
621 | * @sd: information about the splice operation | |
622 | * | |
623 | * Description: | |
624 | * This function will wake up pipe writers if necessary. It should | |
625 | * be called after a loop containing splice_from_pipe_next() and | |
626 | * splice_from_pipe_feed(). | |
627 | */ | |
96f9bc8f | 628 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd MS |
629 | { |
630 | if (sd->need_wakeup) | |
631 | wakeup_pipe_writers(pipe); | |
632 | } | |
5274f052 | 633 | |
b3c2d2dd MS |
634 | /** |
635 | * __splice_from_pipe - splice data from a pipe to given actor | |
636 | * @pipe: pipe to splice from | |
637 | * @sd: information to @actor | |
638 | * @actor: handler that splices the data | |
639 | * | |
640 | * Description: | |
641 | * This function does little more than loop over the pipe and call | |
642 | * @actor to do the actual moving of a single struct pipe_buffer to | |
643 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
644 | * pipe_to_user. | |
645 | * | |
646 | */ | |
647 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
648 | splice_actor *actor) | |
649 | { | |
650 | int ret; | |
5274f052 | 651 | |
b3c2d2dd MS |
652 | splice_from_pipe_begin(sd); |
653 | do { | |
c2489e07 | 654 | cond_resched(); |
b3c2d2dd MS |
655 | ret = splice_from_pipe_next(pipe, sd); |
656 | if (ret > 0) | |
657 | ret = splice_from_pipe_feed(pipe, sd, actor); | |
658 | } while (ret > 0); | |
659 | splice_from_pipe_end(pipe, sd); | |
660 | ||
661 | return sd->num_spliced ? sd->num_spliced : ret; | |
5274f052 | 662 | } |
40bee44e | 663 | EXPORT_SYMBOL(__splice_from_pipe); |
5274f052 | 664 | |
932cc6d4 JA |
665 | /** |
666 | * splice_from_pipe - splice data from a pipe to a file | |
667 | * @pipe: pipe to splice from | |
668 | * @out: file to splice to | |
669 | * @ppos: position in @out | |
670 | * @len: how many bytes to splice | |
671 | * @flags: splice modifier flags | |
672 | * @actor: handler that splices the data | |
673 | * | |
674 | * Description: | |
2933970b | 675 | * See __splice_from_pipe. This function locks the pipe inode, |
932cc6d4 JA |
676 | * otherwise it's identical to __splice_from_pipe(). |
677 | * | |
678 | */ | |
6da61809 MF |
679 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
680 | loff_t *ppos, size_t len, unsigned int flags, | |
681 | splice_actor *actor) | |
682 | { | |
683 | ssize_t ret; | |
c66ab6fa JA |
684 | struct splice_desc sd = { |
685 | .total_len = len, | |
686 | .flags = flags, | |
687 | .pos = *ppos, | |
6a14b90b | 688 | .u.file = out, |
c66ab6fa | 689 | }; |
6da61809 | 690 | |
61e0d47c | 691 | pipe_lock(pipe); |
c66ab6fa | 692 | ret = __splice_from_pipe(pipe, &sd, actor); |
61e0d47c | 693 | pipe_unlock(pipe); |
6da61809 MF |
694 | |
695 | return ret; | |
696 | } | |
697 | ||
8d020765 AV |
698 | /** |
699 | * iter_file_splice_write - splice data from a pipe to a file | |
700 | * @pipe: pipe info | |
701 | * @out: file to write to | |
702 | * @ppos: position in @out | |
703 | * @len: number of bytes to splice | |
704 | * @flags: splice modifier flags | |
705 | * | |
706 | * Description: | |
707 | * Will either move or copy pages (determined by @flags options) from | |
708 | * the given pipe inode to the given file. | |
709 | * This one is ->write_iter-based. | |
710 | * | |
711 | */ | |
712 | ssize_t | |
713 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
714 | loff_t *ppos, size_t len, unsigned int flags) | |
715 | { | |
716 | struct splice_desc sd = { | |
717 | .total_len = len, | |
718 | .flags = flags, | |
719 | .pos = *ppos, | |
720 | .u.file = out, | |
721 | }; | |
722 | int nbufs = pipe->buffers; | |
723 | struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), | |
724 | GFP_KERNEL); | |
725 | ssize_t ret; | |
726 | ||
727 | if (unlikely(!array)) | |
728 | return -ENOMEM; | |
729 | ||
730 | pipe_lock(pipe); | |
731 | ||
732 | splice_from_pipe_begin(&sd); | |
733 | while (sd.total_len) { | |
734 | struct iov_iter from; | |
8d020765 AV |
735 | size_t left; |
736 | int n, idx; | |
737 | ||
738 | ret = splice_from_pipe_next(pipe, &sd); | |
739 | if (ret <= 0) | |
740 | break; | |
741 | ||
742 | if (unlikely(nbufs < pipe->buffers)) { | |
743 | kfree(array); | |
744 | nbufs = pipe->buffers; | |
745 | array = kcalloc(nbufs, sizeof(struct bio_vec), | |
746 | GFP_KERNEL); | |
747 | if (!array) { | |
748 | ret = -ENOMEM; | |
749 | break; | |
750 | } | |
751 | } | |
752 | ||
753 | /* build the vector */ | |
754 | left = sd.total_len; | |
755 | for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) { | |
756 | struct pipe_buffer *buf = pipe->bufs + idx; | |
757 | size_t this_len = buf->len; | |
758 | ||
759 | if (this_len > left) | |
760 | this_len = left; | |
761 | ||
762 | if (idx == pipe->buffers - 1) | |
763 | idx = -1; | |
764 | ||
765 | ret = buf->ops->confirm(pipe, buf); | |
766 | if (unlikely(ret)) { | |
767 | if (ret == -ENODATA) | |
768 | ret = 0; | |
769 | goto done; | |
770 | } | |
771 | ||
772 | array[n].bv_page = buf->page; | |
773 | array[n].bv_len = this_len; | |
774 | array[n].bv_offset = buf->offset; | |
775 | left -= this_len; | |
776 | } | |
777 | ||
05afcb77 AV |
778 | iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n, |
779 | sd.total_len - left); | |
dbe4e192 | 780 | ret = vfs_iter_write(out, &from, &sd.pos); |
8d020765 AV |
781 | if (ret <= 0) |
782 | break; | |
783 | ||
784 | sd.num_spliced += ret; | |
785 | sd.total_len -= ret; | |
dbe4e192 | 786 | *ppos = sd.pos; |
8d020765 AV |
787 | |
788 | /* dismiss the fully eaten buffers, adjust the partial one */ | |
789 | while (ret) { | |
790 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
791 | if (ret >= buf->len) { | |
792 | const struct pipe_buf_operations *ops = buf->ops; | |
793 | ret -= buf->len; | |
794 | buf->len = 0; | |
795 | buf->ops = NULL; | |
796 | ops->release(pipe, buf); | |
797 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); | |
798 | pipe->nrbufs--; | |
799 | if (pipe->files) | |
800 | sd.need_wakeup = true; | |
801 | } else { | |
802 | buf->offset += ret; | |
803 | buf->len -= ret; | |
804 | ret = 0; | |
805 | } | |
806 | } | |
807 | } | |
808 | done: | |
809 | kfree(array); | |
810 | splice_from_pipe_end(pipe, &sd); | |
811 | ||
812 | pipe_unlock(pipe); | |
813 | ||
814 | if (sd.num_spliced) | |
815 | ret = sd.num_spliced; | |
816 | ||
817 | return ret; | |
818 | } | |
819 | ||
820 | EXPORT_SYMBOL(iter_file_splice_write); | |
821 | ||
b2858d7d MS |
822 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
823 | struct splice_desc *sd) | |
0b0a47f5 | 824 | { |
b2858d7d MS |
825 | int ret; |
826 | void *data; | |
06ae43f3 | 827 | loff_t tmp = sd->pos; |
b2858d7d | 828 | |
fbb32750 | 829 | data = kmap(buf->page); |
06ae43f3 | 830 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); |
fbb32750 | 831 | kunmap(buf->page); |
b2858d7d MS |
832 | |
833 | return ret; | |
0b0a47f5 MS |
834 | } |
835 | ||
836 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, | |
837 | struct file *out, loff_t *ppos, | |
838 | size_t len, unsigned int flags) | |
839 | { | |
b2858d7d | 840 | ssize_t ret; |
0b0a47f5 | 841 | |
b2858d7d MS |
842 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
843 | if (ret > 0) | |
844 | *ppos += ret; | |
0b0a47f5 | 845 | |
b2858d7d | 846 | return ret; |
0b0a47f5 MS |
847 | } |
848 | ||
83f9135b JA |
849 | /** |
850 | * generic_splice_sendpage - splice data from a pipe to a socket | |
932cc6d4 | 851 | * @pipe: pipe to splice from |
83f9135b | 852 | * @out: socket to write to |
932cc6d4 | 853 | * @ppos: position in @out |
83f9135b JA |
854 | * @len: number of bytes to splice |
855 | * @flags: splice modifier flags | |
856 | * | |
932cc6d4 JA |
857 | * Description: |
858 | * Will send @len bytes from the pipe to a network socket. No data copying | |
859 | * is involved. | |
83f9135b JA |
860 | * |
861 | */ | |
3a326a2c | 862 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 863 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 864 | { |
00522fb4 | 865 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
866 | } |
867 | ||
059a8f37 | 868 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 869 | |
83f9135b JA |
870 | /* |
871 | * Attempt to initiate a splice from pipe to file. | |
872 | */ | |
3a326a2c | 873 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 874 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 875 | { |
0b0a47f5 MS |
876 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
877 | loff_t *, size_t, unsigned int); | |
5274f052 | 878 | |
72c2d531 | 879 | if (out->f_op->splice_write) |
cc56f7de CG |
880 | splice_write = out->f_op->splice_write; |
881 | else | |
0b0a47f5 MS |
882 | splice_write = default_file_splice_write; |
883 | ||
500368f7 | 884 | return splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
885 | } |
886 | ||
83f9135b JA |
887 | /* |
888 | * Attempt to initiate a splice from a file to a pipe. | |
889 | */ | |
cbb7e577 JA |
890 | static long do_splice_to(struct file *in, loff_t *ppos, |
891 | struct pipe_inode_info *pipe, size_t len, | |
892 | unsigned int flags) | |
5274f052 | 893 | { |
6818173b MS |
894 | ssize_t (*splice_read)(struct file *, loff_t *, |
895 | struct pipe_inode_info *, size_t, unsigned int); | |
5274f052 JA |
896 | int ret; |
897 | ||
49570e9b | 898 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
899 | return -EBADF; |
900 | ||
cbb7e577 | 901 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
902 | if (unlikely(ret < 0)) |
903 | return ret; | |
904 | ||
03cc0789 AV |
905 | if (unlikely(len > MAX_RW_COUNT)) |
906 | len = MAX_RW_COUNT; | |
907 | ||
72c2d531 | 908 | if (in->f_op->splice_read) |
cc56f7de CG |
909 | splice_read = in->f_op->splice_read; |
910 | else | |
6818173b MS |
911 | splice_read = default_file_splice_read; |
912 | ||
913 | return splice_read(in, ppos, pipe, len, flags); | |
5274f052 JA |
914 | } |
915 | ||
932cc6d4 JA |
916 | /** |
917 | * splice_direct_to_actor - splices data directly between two non-pipes | |
918 | * @in: file to splice from | |
919 | * @sd: actor information on where to splice to | |
920 | * @actor: handles the data splicing | |
921 | * | |
922 | * Description: | |
923 | * This is a special case helper to splice directly between two | |
924 | * points, without requiring an explicit pipe. Internally an allocated | |
79685b8d | 925 | * pipe is cached in the process, and reused during the lifetime of |
932cc6d4 JA |
926 | * that process. |
927 | * | |
c66ab6fa JA |
928 | */ |
929 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
930 | splice_direct_actor *actor) | |
b92ce558 JA |
931 | { |
932 | struct pipe_inode_info *pipe; | |
933 | long ret, bytes; | |
934 | umode_t i_mode; | |
c66ab6fa | 935 | size_t len; |
0ff28d9f | 936 | int i, flags, more; |
b92ce558 JA |
937 | |
938 | /* | |
939 | * We require the input being a regular file, as we don't want to | |
940 | * randomly drop data for eg socket -> socket splicing. Use the | |
941 | * piped splicing for that! | |
942 | */ | |
496ad9aa | 943 | i_mode = file_inode(in)->i_mode; |
b92ce558 JA |
944 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
945 | return -EINVAL; | |
946 | ||
947 | /* | |
948 | * neither in nor out is a pipe, setup an internal pipe attached to | |
949 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
950 | */ | |
951 | pipe = current->splice_pipe; | |
49570e9b | 952 | if (unlikely(!pipe)) { |
7bee130e | 953 | pipe = alloc_pipe_info(); |
b92ce558 JA |
954 | if (!pipe) |
955 | return -ENOMEM; | |
956 | ||
957 | /* | |
958 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 959 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
960 | * PIPE_READERS appropriately. |
961 | */ | |
962 | pipe->readers = 1; | |
963 | ||
964 | current->splice_pipe = pipe; | |
965 | } | |
966 | ||
967 | /* | |
73d62d83 | 968 | * Do the splice. |
b92ce558 JA |
969 | */ |
970 | ret = 0; | |
971 | bytes = 0; | |
c66ab6fa JA |
972 | len = sd->total_len; |
973 | flags = sd->flags; | |
974 | ||
975 | /* | |
976 | * Don't block on output, we have to drain the direct pipe. | |
977 | */ | |
978 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
0ff28d9f | 979 | more = sd->flags & SPLICE_F_MORE; |
b92ce558 JA |
980 | |
981 | while (len) { | |
51a92c0f | 982 | size_t read_len; |
a82c53a0 | 983 | loff_t pos = sd->pos, prev_pos = pos; |
b92ce558 | 984 | |
bcd4f3ac | 985 | ret = do_splice_to(in, &pos, pipe, len, flags); |
51a92c0f | 986 | if (unlikely(ret <= 0)) |
b92ce558 JA |
987 | goto out_release; |
988 | ||
989 | read_len = ret; | |
c66ab6fa | 990 | sd->total_len = read_len; |
b92ce558 | 991 | |
0ff28d9f CL |
992 | /* |
993 | * If more data is pending, set SPLICE_F_MORE | |
994 | * If this is the last data and SPLICE_F_MORE was not set | |
995 | * initially, clears it. | |
996 | */ | |
997 | if (read_len < len) | |
998 | sd->flags |= SPLICE_F_MORE; | |
999 | else if (!more) | |
1000 | sd->flags &= ~SPLICE_F_MORE; | |
b92ce558 JA |
1001 | /* |
1002 | * NOTE: nonblocking mode only applies to the input. We | |
1003 | * must not do the output in nonblocking mode as then we | |
1004 | * could get stuck data in the internal pipe: | |
1005 | */ | |
c66ab6fa | 1006 | ret = actor(pipe, sd); |
a82c53a0 TZ |
1007 | if (unlikely(ret <= 0)) { |
1008 | sd->pos = prev_pos; | |
b92ce558 | 1009 | goto out_release; |
a82c53a0 | 1010 | } |
b92ce558 JA |
1011 | |
1012 | bytes += ret; | |
1013 | len -= ret; | |
bcd4f3ac | 1014 | sd->pos = pos; |
b92ce558 | 1015 | |
a82c53a0 TZ |
1016 | if (ret < read_len) { |
1017 | sd->pos = prev_pos + ret; | |
51a92c0f | 1018 | goto out_release; |
a82c53a0 | 1019 | } |
b92ce558 JA |
1020 | } |
1021 | ||
9e97198d | 1022 | done: |
b92ce558 | 1023 | pipe->nrbufs = pipe->curbuf = 0; |
80848708 | 1024 | file_accessed(in); |
b92ce558 JA |
1025 | return bytes; |
1026 | ||
1027 | out_release: | |
1028 | /* | |
1029 | * If we did an incomplete transfer we must release | |
1030 | * the pipe buffers in question: | |
1031 | */ | |
35f3d14d | 1032 | for (i = 0; i < pipe->buffers; i++) { |
b92ce558 JA |
1033 | struct pipe_buffer *buf = pipe->bufs + i; |
1034 | ||
1035 | if (buf->ops) { | |
1036 | buf->ops->release(pipe, buf); | |
1037 | buf->ops = NULL; | |
1038 | } | |
1039 | } | |
b92ce558 | 1040 | |
9e97198d JA |
1041 | if (!bytes) |
1042 | bytes = ret; | |
c66ab6fa | 1043 | |
9e97198d | 1044 | goto done; |
c66ab6fa JA |
1045 | } |
1046 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1047 | ||
1048 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1049 | struct splice_desc *sd) | |
1050 | { | |
6a14b90b | 1051 | struct file *file = sd->u.file; |
c66ab6fa | 1052 | |
7995bd28 | 1053 | return do_splice_from(pipe, file, sd->opos, sd->total_len, |
2cb4b05e | 1054 | sd->flags); |
c66ab6fa JA |
1055 | } |
1056 | ||
932cc6d4 JA |
1057 | /** |
1058 | * do_splice_direct - splices data directly between two files | |
1059 | * @in: file to splice from | |
1060 | * @ppos: input file offset | |
1061 | * @out: file to splice to | |
acdb37c3 | 1062 | * @opos: output file offset |
932cc6d4 JA |
1063 | * @len: number of bytes to splice |
1064 | * @flags: splice modifier flags | |
1065 | * | |
1066 | * Description: | |
1067 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1068 | * doing it in the application would incur an extra system call | |
1069 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1070 | * can splice directly through a process-private pipe. | |
1071 | * | |
1072 | */ | |
c66ab6fa | 1073 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
7995bd28 | 1074 | loff_t *opos, size_t len, unsigned int flags) |
c66ab6fa JA |
1075 | { |
1076 | struct splice_desc sd = { | |
1077 | .len = len, | |
1078 | .total_len = len, | |
1079 | .flags = flags, | |
1080 | .pos = *ppos, | |
6a14b90b | 1081 | .u.file = out, |
7995bd28 | 1082 | .opos = opos, |
c66ab6fa | 1083 | }; |
51a92c0f | 1084 | long ret; |
c66ab6fa | 1085 | |
18c67cb9 AV |
1086 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1087 | return -EBADF; | |
1088 | ||
1089 | if (unlikely(out->f_flags & O_APPEND)) | |
1090 | return -EINVAL; | |
1091 | ||
1092 | ret = rw_verify_area(WRITE, out, opos, len); | |
1093 | if (unlikely(ret < 0)) | |
1094 | return ret; | |
1095 | ||
c66ab6fa | 1096 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
51a92c0f | 1097 | if (ret > 0) |
a82c53a0 | 1098 | *ppos = sd.pos; |
51a92c0f | 1099 | |
c66ab6fa | 1100 | return ret; |
b92ce558 | 1101 | } |
1c118596 | 1102 | EXPORT_SYMBOL(do_splice_direct); |
b92ce558 | 1103 | |
8924feff AV |
1104 | static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) |
1105 | { | |
1106 | while (pipe->nrbufs == pipe->buffers) { | |
1107 | if (flags & SPLICE_F_NONBLOCK) | |
1108 | return -EAGAIN; | |
1109 | if (signal_pending(current)) | |
1110 | return -ERESTARTSYS; | |
1111 | pipe->waiting_writers++; | |
1112 | pipe_wait(pipe); | |
1113 | pipe->waiting_writers--; | |
1114 | } | |
1115 | return 0; | |
1116 | } | |
1117 | ||
7c77f0b3 MS |
1118 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1119 | struct pipe_inode_info *opipe, | |
1120 | size_t len, unsigned int flags); | |
ddac0d39 | 1121 | |
83f9135b JA |
1122 | /* |
1123 | * Determine where to splice to/from. | |
1124 | */ | |
529565dc IM |
1125 | static long do_splice(struct file *in, loff_t __user *off_in, |
1126 | struct file *out, loff_t __user *off_out, | |
1127 | size_t len, unsigned int flags) | |
5274f052 | 1128 | { |
7c77f0b3 MS |
1129 | struct pipe_inode_info *ipipe; |
1130 | struct pipe_inode_info *opipe; | |
7995bd28 | 1131 | loff_t offset; |
a4514ebd | 1132 | long ret; |
5274f052 | 1133 | |
71993e62 LT |
1134 | ipipe = get_pipe_info(in); |
1135 | opipe = get_pipe_info(out); | |
7c77f0b3 MS |
1136 | |
1137 | if (ipipe && opipe) { | |
1138 | if (off_in || off_out) | |
1139 | return -ESPIPE; | |
1140 | ||
1141 | if (!(in->f_mode & FMODE_READ)) | |
1142 | return -EBADF; | |
1143 | ||
1144 | if (!(out->f_mode & FMODE_WRITE)) | |
1145 | return -EBADF; | |
1146 | ||
1147 | /* Splicing to self would be fun, but... */ | |
1148 | if (ipipe == opipe) | |
1149 | return -EINVAL; | |
1150 | ||
1151 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); | |
1152 | } | |
1153 | ||
1154 | if (ipipe) { | |
529565dc IM |
1155 | if (off_in) |
1156 | return -ESPIPE; | |
b92ce558 | 1157 | if (off_out) { |
19c9a49b | 1158 | if (!(out->f_mode & FMODE_PWRITE)) |
b92ce558 | 1159 | return -EINVAL; |
cbb7e577 | 1160 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 1161 | return -EFAULT; |
7995bd28 AV |
1162 | } else { |
1163 | offset = out->f_pos; | |
1164 | } | |
529565dc | 1165 | |
18c67cb9 AV |
1166 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1167 | return -EBADF; | |
1168 | ||
1169 | if (unlikely(out->f_flags & O_APPEND)) | |
1170 | return -EINVAL; | |
1171 | ||
1172 | ret = rw_verify_area(WRITE, out, &offset, len); | |
1173 | if (unlikely(ret < 0)) | |
1174 | return ret; | |
1175 | ||
500368f7 | 1176 | file_start_write(out); |
7995bd28 | 1177 | ret = do_splice_from(ipipe, out, &offset, len, flags); |
500368f7 | 1178 | file_end_write(out); |
a4514ebd | 1179 | |
7995bd28 AV |
1180 | if (!off_out) |
1181 | out->f_pos = offset; | |
1182 | else if (copy_to_user(off_out, &offset, sizeof(loff_t))) | |
a4514ebd JA |
1183 | ret = -EFAULT; |
1184 | ||
1185 | return ret; | |
529565dc | 1186 | } |
5274f052 | 1187 | |
7c77f0b3 | 1188 | if (opipe) { |
529565dc IM |
1189 | if (off_out) |
1190 | return -ESPIPE; | |
b92ce558 | 1191 | if (off_in) { |
19c9a49b | 1192 | if (!(in->f_mode & FMODE_PREAD)) |
b92ce558 | 1193 | return -EINVAL; |
cbb7e577 | 1194 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 1195 | return -EFAULT; |
7995bd28 AV |
1196 | } else { |
1197 | offset = in->f_pos; | |
1198 | } | |
529565dc | 1199 | |
8924feff AV |
1200 | pipe_lock(opipe); |
1201 | ret = wait_for_space(opipe, flags); | |
1202 | if (!ret) | |
1203 | ret = do_splice_to(in, &offset, opipe, len, flags); | |
1204 | pipe_unlock(opipe); | |
1205 | if (ret > 0) | |
1206 | wakeup_pipe_readers(opipe); | |
7995bd28 AV |
1207 | if (!off_in) |
1208 | in->f_pos = offset; | |
1209 | else if (copy_to_user(off_in, &offset, sizeof(loff_t))) | |
a4514ebd JA |
1210 | ret = -EFAULT; |
1211 | ||
1212 | return ret; | |
529565dc | 1213 | } |
5274f052 JA |
1214 | |
1215 | return -EINVAL; | |
1216 | } | |
1217 | ||
79fddc4e AV |
1218 | static int iter_to_pipe(struct iov_iter *from, |
1219 | struct pipe_inode_info *pipe, | |
1220 | unsigned flags) | |
912d35f8 | 1221 | { |
79fddc4e AV |
1222 | struct pipe_buffer buf = { |
1223 | .ops = &user_page_pipe_buf_ops, | |
1224 | .flags = flags | |
1225 | }; | |
1226 | size_t total = 0; | |
1227 | int ret = 0; | |
1228 | bool failed = false; | |
1229 | ||
1230 | while (iov_iter_count(from) && !failed) { | |
1231 | struct page *pages[16]; | |
db85a9eb AV |
1232 | ssize_t copied; |
1233 | size_t start; | |
79fddc4e | 1234 | int n; |
db85a9eb | 1235 | |
79fddc4e AV |
1236 | copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start); |
1237 | if (copied <= 0) { | |
1238 | ret = copied; | |
1239 | break; | |
1240 | } | |
db85a9eb | 1241 | |
79fddc4e | 1242 | for (n = 0; copied; n++, start = 0) { |
db85a9eb | 1243 | int size = min_t(int, copied, PAGE_SIZE - start); |
79fddc4e AV |
1244 | if (!failed) { |
1245 | buf.page = pages[n]; | |
1246 | buf.offset = start; | |
1247 | buf.len = size; | |
1248 | ret = add_to_pipe(pipe, &buf); | |
1249 | if (unlikely(ret < 0)) { | |
1250 | failed = true; | |
1251 | } else { | |
1252 | iov_iter_advance(from, ret); | |
1253 | total += ret; | |
1254 | } | |
1255 | } else { | |
1256 | put_page(pages[n]); | |
1257 | } | |
db85a9eb | 1258 | copied -= size; |
912d35f8 | 1259 | } |
912d35f8 | 1260 | } |
79fddc4e | 1261 | return total ? total : ret; |
912d35f8 JA |
1262 | } |
1263 | ||
6a14b90b JA |
1264 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1265 | struct splice_desc *sd) | |
1266 | { | |
6130f531 AV |
1267 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); |
1268 | return n == sd->len ? n : -EFAULT; | |
6a14b90b JA |
1269 | } |
1270 | ||
1271 | /* | |
1272 | * For lack of a better implementation, implement vmsplice() to userspace | |
1273 | * as a simple copy of the pipes pages to the user iov. | |
1274 | */ | |
6130f531 | 1275 | static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov, |
6a14b90b JA |
1276 | unsigned long nr_segs, unsigned int flags) |
1277 | { | |
1278 | struct pipe_inode_info *pipe; | |
1279 | struct splice_desc sd; | |
6a14b90b | 1280 | long ret; |
6130f531 AV |
1281 | struct iovec iovstack[UIO_FASTIOV]; |
1282 | struct iovec *iov = iovstack; | |
1283 | struct iov_iter iter; | |
6a14b90b | 1284 | |
71993e62 | 1285 | pipe = get_pipe_info(file); |
6a14b90b JA |
1286 | if (!pipe) |
1287 | return -EBADF; | |
1288 | ||
345995fa AV |
1289 | ret = import_iovec(READ, uiov, nr_segs, |
1290 | ARRAY_SIZE(iovstack), &iov, &iter); | |
1291 | if (ret < 0) | |
1292 | return ret; | |
6a14b90b | 1293 | |
345995fa | 1294 | sd.total_len = iov_iter_count(&iter); |
6130f531 | 1295 | sd.len = 0; |
6130f531 AV |
1296 | sd.flags = flags; |
1297 | sd.u.data = &iter; | |
1298 | sd.pos = 0; | |
6a14b90b | 1299 | |
345995fa AV |
1300 | if (sd.total_len) { |
1301 | pipe_lock(pipe); | |
1302 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1303 | pipe_unlock(pipe); | |
1304 | } | |
6a14b90b | 1305 | |
345995fa | 1306 | kfree(iov); |
6a14b90b JA |
1307 | return ret; |
1308 | } | |
1309 | ||
912d35f8 JA |
1310 | /* |
1311 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1312 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1313 | * to file). In both cases the output is a pipe, naturally. | |
912d35f8 | 1314 | */ |
db85a9eb | 1315 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov, |
6a14b90b | 1316 | unsigned long nr_segs, unsigned int flags) |
912d35f8 | 1317 | { |
ddac0d39 | 1318 | struct pipe_inode_info *pipe; |
db85a9eb AV |
1319 | struct iovec iovstack[UIO_FASTIOV]; |
1320 | struct iovec *iov = iovstack; | |
1321 | struct iov_iter from; | |
35f3d14d | 1322 | long ret; |
79fddc4e AV |
1323 | unsigned buf_flag = 0; |
1324 | ||
1325 | if (flags & SPLICE_F_GIFT) | |
1326 | buf_flag = PIPE_BUF_FLAG_GIFT; | |
912d35f8 | 1327 | |
71993e62 | 1328 | pipe = get_pipe_info(file); |
ddac0d39 | 1329 | if (!pipe) |
912d35f8 | 1330 | return -EBADF; |
912d35f8 | 1331 | |
db85a9eb AV |
1332 | ret = import_iovec(WRITE, uiov, nr_segs, |
1333 | ARRAY_SIZE(iovstack), &iov, &from); | |
1334 | if (ret < 0) | |
1335 | return ret; | |
1336 | ||
8924feff AV |
1337 | pipe_lock(pipe); |
1338 | ret = wait_for_space(pipe, flags); | |
79fddc4e AV |
1339 | if (!ret) |
1340 | ret = iter_to_pipe(&from, pipe, buf_flag); | |
8924feff AV |
1341 | pipe_unlock(pipe); |
1342 | if (ret > 0) | |
1343 | wakeup_pipe_readers(pipe); | |
db85a9eb | 1344 | kfree(iov); |
35f3d14d | 1345 | return ret; |
912d35f8 JA |
1346 | } |
1347 | ||
6a14b90b JA |
1348 | /* |
1349 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1350 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1351 | * operation that can be supported without any funky alignment restrictions | |
1352 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1353 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1354 | * solutions for that: | |
1355 | * | |
1356 | * - memcpy() the data internally, at which point we might as well just | |
1357 | * do a regular read() on the buffer anyway. | |
1358 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1359 | * has restriction limitations on both ends of the pipe). | |
1360 | * | |
1361 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1362 | * | |
1363 | */ | |
836f92ad HC |
1364 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
1365 | unsigned long, nr_segs, unsigned int, flags) | |
912d35f8 | 1366 | { |
2903ff01 | 1367 | struct fd f; |
912d35f8 | 1368 | long error; |
912d35f8 | 1369 | |
6a14b90b JA |
1370 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1371 | return -EINVAL; | |
1372 | else if (unlikely(!nr_segs)) | |
1373 | return 0; | |
1374 | ||
912d35f8 | 1375 | error = -EBADF; |
2903ff01 AV |
1376 | f = fdget(fd); |
1377 | if (f.file) { | |
1378 | if (f.file->f_mode & FMODE_WRITE) | |
1379 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); | |
1380 | else if (f.file->f_mode & FMODE_READ) | |
1381 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); | |
1382 | ||
1383 | fdput(f); | |
912d35f8 JA |
1384 | } |
1385 | ||
1386 | return error; | |
1387 | } | |
1388 | ||
76b021d0 AV |
1389 | #ifdef CONFIG_COMPAT |
1390 | COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32, | |
1391 | unsigned int, nr_segs, unsigned int, flags) | |
1392 | { | |
1393 | unsigned i; | |
1394 | struct iovec __user *iov; | |
1395 | if (nr_segs > UIO_MAXIOV) | |
1396 | return -EINVAL; | |
1397 | iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec)); | |
1398 | for (i = 0; i < nr_segs; i++) { | |
1399 | struct compat_iovec v; | |
1400 | if (get_user(v.iov_base, &iov32[i].iov_base) || | |
1401 | get_user(v.iov_len, &iov32[i].iov_len) || | |
1402 | put_user(compat_ptr(v.iov_base), &iov[i].iov_base) || | |
1403 | put_user(v.iov_len, &iov[i].iov_len)) | |
1404 | return -EFAULT; | |
1405 | } | |
1406 | return sys_vmsplice(fd, iov, nr_segs, flags); | |
1407 | } | |
1408 | #endif | |
1409 | ||
836f92ad HC |
1410 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1411 | int, fd_out, loff_t __user *, off_out, | |
1412 | size_t, len, unsigned int, flags) | |
5274f052 | 1413 | { |
2903ff01 | 1414 | struct fd in, out; |
5274f052 | 1415 | long error; |
5274f052 JA |
1416 | |
1417 | if (unlikely(!len)) | |
1418 | return 0; | |
1419 | ||
1420 | error = -EBADF; | |
2903ff01 AV |
1421 | in = fdget(fd_in); |
1422 | if (in.file) { | |
1423 | if (in.file->f_mode & FMODE_READ) { | |
1424 | out = fdget(fd_out); | |
1425 | if (out.file) { | |
1426 | if (out.file->f_mode & FMODE_WRITE) | |
1427 | error = do_splice(in.file, off_in, | |
1428 | out.file, off_out, | |
529565dc | 1429 | len, flags); |
2903ff01 | 1430 | fdput(out); |
5274f052 JA |
1431 | } |
1432 | } | |
2903ff01 | 1433 | fdput(in); |
5274f052 | 1434 | } |
5274f052 JA |
1435 | return error; |
1436 | } | |
70524490 | 1437 | |
aadd06e5 JA |
1438 | /* |
1439 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1440 | * return an appropriate error. | |
1441 | */ | |
7c77f0b3 | 1442 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1443 | { |
1444 | int ret; | |
1445 | ||
1446 | /* | |
1447 | * Check ->nrbufs without the inode lock first. This function | |
1448 | * is speculative anyways, so missing one is ok. | |
1449 | */ | |
1450 | if (pipe->nrbufs) | |
1451 | return 0; | |
1452 | ||
1453 | ret = 0; | |
61e0d47c | 1454 | pipe_lock(pipe); |
aadd06e5 JA |
1455 | |
1456 | while (!pipe->nrbufs) { | |
1457 | if (signal_pending(current)) { | |
1458 | ret = -ERESTARTSYS; | |
1459 | break; | |
1460 | } | |
1461 | if (!pipe->writers) | |
1462 | break; | |
1463 | if (!pipe->waiting_writers) { | |
1464 | if (flags & SPLICE_F_NONBLOCK) { | |
1465 | ret = -EAGAIN; | |
1466 | break; | |
1467 | } | |
1468 | } | |
1469 | pipe_wait(pipe); | |
1470 | } | |
1471 | ||
61e0d47c | 1472 | pipe_unlock(pipe); |
aadd06e5 JA |
1473 | return ret; |
1474 | } | |
1475 | ||
1476 | /* | |
1477 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1478 | * return an appropriate error. | |
1479 | */ | |
7c77f0b3 | 1480 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1481 | { |
1482 | int ret; | |
1483 | ||
1484 | /* | |
1485 | * Check ->nrbufs without the inode lock first. This function | |
1486 | * is speculative anyways, so missing one is ok. | |
1487 | */ | |
35f3d14d | 1488 | if (pipe->nrbufs < pipe->buffers) |
aadd06e5 JA |
1489 | return 0; |
1490 | ||
1491 | ret = 0; | |
61e0d47c | 1492 | pipe_lock(pipe); |
aadd06e5 | 1493 | |
35f3d14d | 1494 | while (pipe->nrbufs >= pipe->buffers) { |
aadd06e5 JA |
1495 | if (!pipe->readers) { |
1496 | send_sig(SIGPIPE, current, 0); | |
1497 | ret = -EPIPE; | |
1498 | break; | |
1499 | } | |
1500 | if (flags & SPLICE_F_NONBLOCK) { | |
1501 | ret = -EAGAIN; | |
1502 | break; | |
1503 | } | |
1504 | if (signal_pending(current)) { | |
1505 | ret = -ERESTARTSYS; | |
1506 | break; | |
1507 | } | |
1508 | pipe->waiting_writers++; | |
1509 | pipe_wait(pipe); | |
1510 | pipe->waiting_writers--; | |
1511 | } | |
1512 | ||
61e0d47c | 1513 | pipe_unlock(pipe); |
aadd06e5 JA |
1514 | return ret; |
1515 | } | |
1516 | ||
7c77f0b3 MS |
1517 | /* |
1518 | * Splice contents of ipipe to opipe. | |
1519 | */ | |
1520 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1521 | struct pipe_inode_info *opipe, | |
1522 | size_t len, unsigned int flags) | |
1523 | { | |
1524 | struct pipe_buffer *ibuf, *obuf; | |
1525 | int ret = 0, nbuf; | |
1526 | bool input_wakeup = false; | |
1527 | ||
1528 | ||
1529 | retry: | |
1530 | ret = ipipe_prep(ipipe, flags); | |
1531 | if (ret) | |
1532 | return ret; | |
1533 | ||
1534 | ret = opipe_prep(opipe, flags); | |
1535 | if (ret) | |
1536 | return ret; | |
1537 | ||
1538 | /* | |
1539 | * Potential ABBA deadlock, work around it by ordering lock | |
1540 | * grabbing by pipe info address. Otherwise two different processes | |
1541 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1542 | */ | |
1543 | pipe_double_lock(ipipe, opipe); | |
1544 | ||
1545 | do { | |
1546 | if (!opipe->readers) { | |
1547 | send_sig(SIGPIPE, current, 0); | |
1548 | if (!ret) | |
1549 | ret = -EPIPE; | |
1550 | break; | |
1551 | } | |
1552 | ||
1553 | if (!ipipe->nrbufs && !ipipe->writers) | |
1554 | break; | |
1555 | ||
1556 | /* | |
1557 | * Cannot make any progress, because either the input | |
1558 | * pipe is empty or the output pipe is full. | |
1559 | */ | |
35f3d14d | 1560 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { |
7c77f0b3 MS |
1561 | /* Already processed some buffers, break */ |
1562 | if (ret) | |
1563 | break; | |
1564 | ||
1565 | if (flags & SPLICE_F_NONBLOCK) { | |
1566 | ret = -EAGAIN; | |
1567 | break; | |
1568 | } | |
1569 | ||
1570 | /* | |
1571 | * We raced with another reader/writer and haven't | |
1572 | * managed to process any buffers. A zero return | |
1573 | * value means EOF, so retry instead. | |
1574 | */ | |
1575 | pipe_unlock(ipipe); | |
1576 | pipe_unlock(opipe); | |
1577 | goto retry; | |
1578 | } | |
1579 | ||
1580 | ibuf = ipipe->bufs + ipipe->curbuf; | |
35f3d14d | 1581 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
7c77f0b3 MS |
1582 | obuf = opipe->bufs + nbuf; |
1583 | ||
1584 | if (len >= ibuf->len) { | |
1585 | /* | |
1586 | * Simply move the whole buffer from ipipe to opipe | |
1587 | */ | |
1588 | *obuf = *ibuf; | |
1589 | ibuf->ops = NULL; | |
1590 | opipe->nrbufs++; | |
35f3d14d | 1591 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); |
7c77f0b3 MS |
1592 | ipipe->nrbufs--; |
1593 | input_wakeup = true; | |
1594 | } else { | |
1595 | /* | |
1596 | * Get a reference to this pipe buffer, | |
1597 | * so we can copy the contents over. | |
1598 | */ | |
1599 | ibuf->ops->get(ipipe, ibuf); | |
1600 | *obuf = *ibuf; | |
1601 | ||
1602 | /* | |
1603 | * Don't inherit the gift flag, we need to | |
1604 | * prevent multiple steals of this page. | |
1605 | */ | |
1606 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1607 | ||
1608 | obuf->len = len; | |
1609 | opipe->nrbufs++; | |
1610 | ibuf->offset += obuf->len; | |
1611 | ibuf->len -= obuf->len; | |
1612 | } | |
1613 | ret += obuf->len; | |
1614 | len -= obuf->len; | |
1615 | } while (len); | |
1616 | ||
1617 | pipe_unlock(ipipe); | |
1618 | pipe_unlock(opipe); | |
1619 | ||
1620 | /* | |
1621 | * If we put data in the output pipe, wakeup any potential readers. | |
1622 | */ | |
825cdcb1 NK |
1623 | if (ret > 0) |
1624 | wakeup_pipe_readers(opipe); | |
1625 | ||
7c77f0b3 MS |
1626 | if (input_wakeup) |
1627 | wakeup_pipe_writers(ipipe); | |
1628 | ||
1629 | return ret; | |
1630 | } | |
1631 | ||
70524490 JA |
1632 | /* |
1633 | * Link contents of ipipe to opipe. | |
1634 | */ | |
1635 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1636 | struct pipe_inode_info *opipe, | |
1637 | size_t len, unsigned int flags) | |
1638 | { | |
1639 | struct pipe_buffer *ibuf, *obuf; | |
aadd06e5 | 1640 | int ret = 0, i = 0, nbuf; |
70524490 JA |
1641 | |
1642 | /* | |
1643 | * Potential ABBA deadlock, work around it by ordering lock | |
61e0d47c | 1644 | * grabbing by pipe info address. Otherwise two different processes |
70524490 JA |
1645 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1646 | */ | |
61e0d47c | 1647 | pipe_double_lock(ipipe, opipe); |
70524490 | 1648 | |
aadd06e5 | 1649 | do { |
70524490 JA |
1650 | if (!opipe->readers) { |
1651 | send_sig(SIGPIPE, current, 0); | |
1652 | if (!ret) | |
1653 | ret = -EPIPE; | |
1654 | break; | |
1655 | } | |
70524490 | 1656 | |
aadd06e5 JA |
1657 | /* |
1658 | * If we have iterated all input buffers or ran out of | |
1659 | * output room, break. | |
1660 | */ | |
35f3d14d | 1661 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) |
aadd06e5 | 1662 | break; |
70524490 | 1663 | |
35f3d14d JA |
1664 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); |
1665 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
70524490 JA |
1666 | |
1667 | /* | |
aadd06e5 JA |
1668 | * Get a reference to this pipe buffer, |
1669 | * so we can copy the contents over. | |
70524490 | 1670 | */ |
aadd06e5 JA |
1671 | ibuf->ops->get(ipipe, ibuf); |
1672 | ||
1673 | obuf = opipe->bufs + nbuf; | |
1674 | *obuf = *ibuf; | |
1675 | ||
2a27250e | 1676 | /* |
aadd06e5 JA |
1677 | * Don't inherit the gift flag, we need to |
1678 | * prevent multiple steals of this page. | |
2a27250e | 1679 | */ |
aadd06e5 | 1680 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
70524490 | 1681 | |
aadd06e5 JA |
1682 | if (obuf->len > len) |
1683 | obuf->len = len; | |
70524490 | 1684 | |
aadd06e5 JA |
1685 | opipe->nrbufs++; |
1686 | ret += obuf->len; | |
1687 | len -= obuf->len; | |
1688 | i++; | |
1689 | } while (len); | |
70524490 | 1690 | |
02cf01ae JA |
1691 | /* |
1692 | * return EAGAIN if we have the potential of some data in the | |
1693 | * future, otherwise just return 0 | |
1694 | */ | |
1695 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) | |
1696 | ret = -EAGAIN; | |
1697 | ||
61e0d47c MS |
1698 | pipe_unlock(ipipe); |
1699 | pipe_unlock(opipe); | |
70524490 | 1700 | |
aadd06e5 JA |
1701 | /* |
1702 | * If we put data in the output pipe, wakeup any potential readers. | |
1703 | */ | |
825cdcb1 NK |
1704 | if (ret > 0) |
1705 | wakeup_pipe_readers(opipe); | |
70524490 JA |
1706 | |
1707 | return ret; | |
1708 | } | |
1709 | ||
1710 | /* | |
1711 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1712 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1713 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1714 | * applicable one is SPLICE_F_NONBLOCK. | |
1715 | */ | |
1716 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1717 | unsigned int flags) | |
1718 | { | |
71993e62 LT |
1719 | struct pipe_inode_info *ipipe = get_pipe_info(in); |
1720 | struct pipe_inode_info *opipe = get_pipe_info(out); | |
aadd06e5 | 1721 | int ret = -EINVAL; |
70524490 JA |
1722 | |
1723 | /* | |
aadd06e5 JA |
1724 | * Duplicate the contents of ipipe to opipe without actually |
1725 | * copying the data. | |
70524490 | 1726 | */ |
aadd06e5 JA |
1727 | if (ipipe && opipe && ipipe != opipe) { |
1728 | /* | |
1729 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1730 | * ordering doesn't really matter. | |
1731 | */ | |
7c77f0b3 | 1732 | ret = ipipe_prep(ipipe, flags); |
aadd06e5 | 1733 | if (!ret) { |
7c77f0b3 | 1734 | ret = opipe_prep(opipe, flags); |
02cf01ae | 1735 | if (!ret) |
aadd06e5 | 1736 | ret = link_pipe(ipipe, opipe, len, flags); |
aadd06e5 JA |
1737 | } |
1738 | } | |
70524490 | 1739 | |
aadd06e5 | 1740 | return ret; |
70524490 JA |
1741 | } |
1742 | ||
836f92ad | 1743 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
70524490 | 1744 | { |
2903ff01 AV |
1745 | struct fd in; |
1746 | int error; | |
70524490 JA |
1747 | |
1748 | if (unlikely(!len)) | |
1749 | return 0; | |
1750 | ||
1751 | error = -EBADF; | |
2903ff01 AV |
1752 | in = fdget(fdin); |
1753 | if (in.file) { | |
1754 | if (in.file->f_mode & FMODE_READ) { | |
1755 | struct fd out = fdget(fdout); | |
1756 | if (out.file) { | |
1757 | if (out.file->f_mode & FMODE_WRITE) | |
1758 | error = do_tee(in.file, out.file, | |
1759 | len, flags); | |
1760 | fdput(out); | |
70524490 JA |
1761 | } |
1762 | } | |
2903ff01 | 1763 | fdput(in); |
70524490 JA |
1764 | } |
1765 | ||
1766 | return error; | |
1767 | } |